The present invention relates to a cooled merchandizing unit. More particularly, the present invention relates to a portable cooled (e.g., refrigeration and/or freezer) merchandizing unit having a thermoelectric assembly and means for circulating air from the thermoelectric assembly through a product container.
Perishable food items are frequently displayed and sold in grocery stores. Some perishable food items are maintained in inventory year-round and are often placed in a permanent merchandizing unit. Other perishable food items are offered during promotions, and are better suited to temporary cooling displays. Some temporary cooling displays are disposable cases employing ice packs and ice to cool the perishable items, and grocers, due to the limited cooling capacity, disfavor these disposable units. Another disincentive to the use of disposable cooling units is the cost associated with their disposal. To this end, grocers have a need for temporary cooling displays that are effective in safely cooling perishable food items. Similar needs arise for temporary cooling displays of frozen food items.
Conventional refrigerators and freezers employed as temporary cooling displays are disfavored due primarily to their expense and non-steady cooling temperatures. As a point of reference, conventional refrigerators and freezers generally include an insulated enclosure having a centralized cooling system employing a vapor compression cycle refrigerant. The cooling system is usually characterized as having a greater cooling capacity than the actual heat load, and this results in the cooling system acting intermittently in a binary duty cycle. That is to say, the cooling system is either on or off. The binary duty cycle is associated with temperature variations inside the insulated the enclosure. For example, when the compressor is off, the temperature in the enclosure increases until reaching an upper limit where the compressor is cycled on. Conversely, when the compressor is on, the temperature in the enclosure decreases until reaching a lower limit where the compressor is cycled off. Thus, the temperature in a conventional refrigerator or freezer is not steady, but cycles between pre-selected upper and lower limits.
In addition, vapor compression cooling systems frequently employ fluorinated hydrocarbons (for example, Freon®) as the refrigerant. The deleterious effects of fluorinated hydrocarbons on the environment are well known, and both national and international regulations are in effect to limit the use of such fluorinated hydrocarbons as refrigerants.
With the above in mind, cooling systems that employ thermoelectric devices for cooling are preferred over vapor pressure refrigerators. The use of thermoelectric devices operating on a direct current (DC) voltage system are known in the art and can be employed to maintain a desired temperature in refrigerators and portable coolers. One example of a cooled container employing a thermoelectric device is described in U.S. Pat. No. 4,726,193 titled “Temperature Controlled Picnic Box.” The temperature controlled picnic box is described as having a housing with insulated walls forming a food compartment, an open top, and a lid for enclosing the food compartment. A thermoelectric device for cooling the picnic box is connected to the lid by fasteners. The thermoelectric device is limited in its capacity to cool the picnic box, and the enclosed food compartment is ill suited for temporary cooling displays.
Other thermoelectric devices used as refrigerators are known. One example is a refrigerator employing super insulation materials and having a thermoelectric cooling device disposed within a door, as described in U.S. Pat. No. 5,522,216 titled “Thermoelectric Refrigerator.” The thermoelectric refrigerator described in U.S. Pat. No. 5,522,216 includes an airflow management system. The airflow management system establishes a desired airflow path across the cooling device to provide a cooled refrigerator unit. The cooling delivered by the thermoelectric device is not unlimited, and for this reason, expensive super insulation is positioned around the cabinet to minimize the cooling loss.
All coolers and refrigerators experience the formation of condensation. Condensation forms whenever warm, humid air from the environment interacts with cooled surfaces. For example, humidity in the air will condense on the cooling elements of the refrigerator or freezer and forms liquid condensate. The liquid condensate builds up within the refrigerator or freezer and can undesirably collect on the products that are being cooled. To this end, condensates in cooling systems can buildup and/or eventually drip on the cooled products.
Grocers and merchandisers have a need to display perishable and frozen food items during temporary displays such as promotional events. The known temporary cooling displays can be generally characterized as inefficient in the case of disposable cases, and expensive in the case of refrigerated or freezer cases. Therefore, a need exists for a portable cooled merchandizing unit that is efficient at cooling and inexpensive to operate.